#include<stdio.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<unistd.h>

int main()
{
    close(1);
    umask(0);
    int fd=open("log.txt",O_CREAT|O_WRONLY|O_TRUNC,0666);
    printf("hello\n");
    sleep(5);
    return 0;
}
